With the development of the automotive industry, competitions are intensified. And raising efficiency and reducing costs have become an issue that requires automobile manufacturers' attention. As one of the four major manufacturing processes, stamping plays an important role in automobiles production. Reducing production costs of stamping pieces and reducing die changeover time in coachwork manufacturing are one of the key tasks.
Dies used in automated production lines are normally stored in stacks, and can be installed to a press through a die loading process. While they are in storage, a position-limiting mechanism provided in the dies keeps elastic elements of the dies from being pushed and deformation.
Two conventional methods exist for position limiting of dies in storage. One uses solely a rigid storing limiter. In the die loading process, a slider of the press is adjusted by an operator according to a storing height of a die, so as to lock the die to the press; then, the rigid storing limiter is removed manually, and the slider is adjusted once again according to a working height of the die. This process requires a long die changeover time, and does not support automated die loading. Moreover, the operator has to enter the die working area, posing a serious risk to safety. The other method uses solely a nitrogen gas spring as an elastic storing limiter. This method may meet the requirement of automated die loading and save die loading time. However, when many dies are stacked, the nitrogen gas spring may be compressed too much, losing its function as a storing limiter and causing damages to elastic elements of the dies. Using a nitrogen gas spring with a higher stiffness may allow the stacking of dies, but may also raise costs of the dies significantly and cannot prevent potential gas leak and failure due to long working hours of the dies; hence it cannot prevent damages to elastic elements of the dies.